Modelling of SO2 detection by tin dioxide gas sensors

In studying tin dioxide-based gas sensors under sulphur dioxide, we have confirmed phenomena at the gas/semi-conductor interface during the first and subsequent detections. According to Lalauze et al. [1], the tin dioxide gas sensor is modified by the first SO2 exposure. It appears that modification is due to the adsorption of sulphite and sulphate on the semi-conductor surface. After the first detection, the gas sensor response peaks at 200 degrees C. We have shown that this peak is connected with quantity of SO2 adsorbed during detection at high temperatures (> 200 degrees C), and not low ones. Finally, we propose two mechanisms to explain these results. (C) 1997 Elsevier Science S.A.